A smart DNA nanodevice for ATP-activatable bioimaging and photodynamic therapy

Rational design of activatable photosensitizers for controlled generation of singlet oxygen remains a challenge for precise photodynamic therapy (PDT). Herein, we present an aptamer-based nanodevice for adenosine 5′-triphosphate (ATP)-activatable bioimaging and PDT. The nanodevice is constructed by modifying ATP-responsive duplex DNA units and polyethylene glycol on the surface of a gold nanoparticle (AuNP) through the thiolate-Au chemistry. The DNA units were designed by the hybridization of the ATP aptamer strand with a methylene blue (MB)-modified complementary DNA (cDNA). The close proximity of MB to the surface of AuNP results in the low photodynamic activity of MB (OFF state). Once internalized into cancer cells, the ATP-binding induced conformation switch of aptamer strand leads to the release of the MB-bearing DNA strand from AuNPs, resulting in the activatable generation of singlet oxygen under light irradiation (ON state). We demonstrate that the DNA nanodevice represents a promising platform for ATP-responsive bioimaging and specific PDT in vitro and in vivo. This work highlights a potential way for specific tumor diagnosis and therapy.